1. Field of the Invention
The present invention relates to a thermometer for measuring a temperature of an object under measurement depending on infrared ray energy emitted from the object.
2. Description of Prior Art
Thermometers have been widely known, which use a temperature sensor such as a thermopile and the like. The thermopile is used as a thermometer for measuring a surface temperature of an object under measurement without touching the object, which thermopile absorbs infrared ray energy emitted from an object under measurement, generates an electromotive force depending on the absorbed infrared ray energy, and converts electric characteristics such as changes in the electromotive force into an electric signal to measure a surface temperature of the object. The thermopile detects a temperature difference between the object under measurement and the thermopile itself, and adds an ambient temperature to the detected temperature difference to obtain a temperature of the object.
Further, thermometers using the thermopile calculate a temperature using as a reference a real black object which absorbs absolutely infrared rays, and, therefore, an emissivity is set to calculate a temperature of an object.
When a temperature measurement is made with the above thermometer using the thermopile, the emissivity has to be set for every temperature measurements. Therefore, the thermometers using the thermopile inherently have defects that, when making a temperature measurement of an object, a user is required to know the emissivity of the object, or to have data concerning the emissivity at hand.
Further, the thermopile can receive infrared rays emitted from an object other than the object under measurement. For example, the thermopile receives infrared light rays reflected on members such as a cover provided in the vicinity of the thermopile, and, therefore, the thermopile has another defect that a precise temperature of the object cannot always be measured.
Furthermore, the thermopile memorizes plural temperature data, but if it memorizes only temperature data without other data attached thereto, it is difficult to judge from which object the memorized temperature data was obtained.